A bicycle, also referred to as a bike or cycle, is a vehicle which provides for a human-powered, generally pedal-driven, means to propel the vehicle. Bicycles are generally single-track vehicles, having two wheels attached to a frame, one behind the other. Bicycles generally have a power driven rear wheel and a free spinning turnable front wheel. The term bicycle generally refers to a vehicle having two (bi) circular arrangements (cycle), however, as used in this patent application the term bicycle may also be considered to extend to tricycle and quadcycle vehicles having two side-by-side power driven wheels and/or two side-by-side free spinning wheels. The term bicycle may also include vehicles that have additional wheels used to provide stability, such as stabilizer wheels, out-rigger wheels, or training wheels.
A bicycle may also include supplemental forms of propulsion, such as a motor (sometimes referred to as an electric bicycle) or engine. However a motor or engine driven vehicle similar to that of a bicycle, but without human-powered propulsion means, would be considered a motorcycle and not a bicycle. The term bicycle, as used in this patent application, does not include motorcycles or the like.
Bicycles were introduced in the 19th century in Europe and number more than a billion worldwide. Bicycles are the principal means of transportation in many regions. They also provide a popular form of recreation, and have been adapted for use in military and police applications, in courier services, as children's toys, and in racing.
Bicycles with rear suspension have become popular over the last 20 years. A rear suspension may provide for a smoother ride for both on-road and off-road riders. Rear suspension systems for bicycles are typically hung on the frame and are exposed to the environment. Suspension systems utilizing a spring-damper may fall susceptible to dirt and mud coating a piston rod and possibly damage a seal. Additionally, the motion of an exposed spring-damper may create pinch/catch points for loose clothing, shoe laces, etc. An exposed spring-damper may also be more difficult to clean and provide for an unsightly appearance.
Bicycles often utilize a chain to provide power transfer from a crank to a drive wheel. The entire chain, or at least a portion thereof, is typically exposed to the environment. Exposed bicycle chains, similar to that of exposed suspension systems, may not work as effectively if coated by mud and dirt, may provide for pinch/catch points for loose clothing, and may be difficult to clean. Additionally bicycle chains typically require oil, which may provide for a sticky surface and maintain more dirt and mud leading to additional concerns. An exposed chain may also soil a rider's pant cuffs while riding Chain guards which partially encapsulate a chain can create a bulky envelope, add weight, and cause noise when the chain contacts the chain guard.